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利用西藏东部南迦巴瓦地区的51个临时地震台站所记录的169个远震事件,从中提取出4767条P波射线,通过反演计算得到了西藏东部地壳和上地幔的P波速度结构.水平剖面显示,在西藏东南部裂谷附近从近地表到250km的深度范围均表现为低速异常;从纵剖面结果看,这个低速异常非垂直地向下延伸到约400km深度.综合分析认为,此低速异常可能意味着地幔高温物质上涌,从而为该区裂谷成因的探讨提供了地震学的证据;在此低速异常的东侧出现明显的高速异常,深度从40km延伸到200km,该高速异常可能是大陆闭合遗留的产物,并非俯冲的印度板块;在250～400km的深度范围内,嘉黎断裂以北为低速异常区,以南为高速异常区.该高速异常可能反映了印度板块的北部边界,并在此发生了拆沉.同时表明,在西藏东部印度板块的俯冲未超过嘉黎断裂.
Based on the 169 teleseismic events recorded by 51 temporary seismic stations in the Namjagbarwa area in eastern Tibet, 4767 P-wave radiations were extracted from them and the P-wave velocity structures of the crust and the upper mantle in eastern Tibet were calculated . The horizontal profiles show low-velocity anomalies in the depth range from near surface to 250km near the rift in southeastern Tibet, and the low-velocity anomalies extend non-vertically to a depth of about 400km from the longitudinal profile results.According to the comprehensive analysis, The low-velocity anomaly may mean upwelling of the mantle high-temperature material, which provides seismological evidence for the exploration of the origin of the rift in this area. A clear high-velocity anomaly occurs to the east of this low-velocity anomaly, extending from 40km to 200km in depth. In the depth of 250 ~ 400km, the north of Jiali Fault is low-velocity anomaly and the south is high-velocity anomaly, which may reflect the Indian plate Northern border where the delamination took place and at the same time showed that the subduction of the Indian plate in eastern Tibet did not exceed that of the Jiali fault.